OK – I see that several other people have similar problems with JRuby – including https://jira.codehaus.org/browse/JRUBY-6597
A work around seems to be to tell the program to use a different tmp directory. eg
$ sudo su – hbase
$ mkdir /home/hbase/tmp
$ export HBASE_OPTS=-Djava.io.tmpdir=/home/hbase/tmp
$ hbase shell
2015-03-09 14:45:12,742 INFO [main] Configuration.deprecation: hadoop.native.lib is deprecated. Instead, use io.native.lib.available
HBase Shell; enter ‘help<RETURN>’ for list of supported commands.
Type “exit<RETURN>” to leave the HBase Shell
Version 0.98.4.2.2.0.0-2041-hadoop2, r18e3e58ae6ca5ef5e9c60e3129a1089a8656f91d, Wed Nov 19 15:10:28 EST 2014
hbase(main):001:0>
Success!
